Mark v25 channel 2 problem

[ZorroBoy]

Hi everyone,
I've started having some trouble with my Mark V25 recently and wanted to see if anyone had any advice. I only notice it on channel 2. Switching out the power tubes hasn't fixed it. When playing, the overall volume as well as what I perceive as the treble will increase for a few seconds then decrease back to the original levels all on it's own. Any ideas what I might be looking at? Could a preamp tube cause this?

Thanks for any help

 

[domct203]

Welcome to the forum.

Yes a preamp tube could cause that. You should swap in a known good tube through each position one at a time to see if you find the problem one. All your preamp tubes are shared by both channels per the tube task chart in your manual so check them all.

I wouldn’t just ‘shotgun’ it and just change them all as it just a theory until you find the bad one. It could be something else but checking for a bad tube is where you should always start.

Dom

 

[ZorroBoy]

Welcome to the forum.

Yes a preamp tube could cause that. You should swap in a known good tube through each position one at a time to see if you find the problem one. All your preamp tubes are shared by both channels per the tube task chart in your manual so check them all.

I wouldn’t just ‘shotgun’ it and just change them all as it just a theory until you find the bad one. It could be something else but checking for a bad tube is where you should always start.

Dom

Thanks for your advice. I'll work on doing that. Fingers crossed